Phenology of two endangered Lupinus westianous
populations along Florida’s Gulf Coast
INTRODUCTION
Primary growth observations
(prior to seed dispersal and dormancy)
•70% of the Deer Lake population were small-medium size (Figure 4)
Karen Roybal DeVore
•37% of the Topsail Hill population were small-medium size (Figure 5)
Fort Lewis College and Florida Department of Environmental Protection
Mean viable seed production (Figure 6)
•The mean production for the Topsail population was 93
•The mean production for the Deer Lake population was 28
EXPERIMENTAL DESIGN
Mean primary growth (Figure 7)
•The Deer Lake population experienced a mean of 0.395 cm./month
Field reconnaissance occurred in April and May, 2006, to identify
2 population of Gulf Coast Lupine in each park that represent small to
medium size lupines (0cm-30.48cm) and medium to large lupines
(30.49cm+). Phenological observations were made from May- October,
2006. Within each plot, 30 lupines were randomly identified and
inconspicuously marked with a 4 inch painted nail, which allowed for
continuous measurements throughout the study.
•The Topsail Hill population experienced an mean of 1.026 cm./month
General observations (Table 1)
•Inflorescence for both populations began in late April
Figure 3. Unobtrusive cheesecloth
encasements were used in attaining
seed count and identification of viable
seeds. Encasements were
constructed according to the
individual plant being observed.
Cheesecloth will encase the plant,
attached to the wooden frame,
allowed for collection and observation
of seed shatter.
STATISTICAL ANALYSIS
Number of flowers, total number of seeds, and seed/flower ratio
will determine the fertility of individual plants. A two-sample t test will be
used to determine reproductive and phenological variation between the two
populations if the data are normally distributed. n=2, p=0.05.
• Anthesis for both populations occurred in early May.
•Topsail State Park, flowers were generally smaller and a lighter shade of
purple, which were observed until mid May.
•The flowers of the Deer Lake population were found to be larger and
darker in coloration, remaining until early June.
•Bees were observed within the Topsail lupine flowers
Figure3. Gulf Coast Lupine infloresence and
seed set; May 2006.
• Upon collection of the cheesecloth encasements of Deer Lake, small
chew holes were observed.
FIELD METHODS
For each lupine, observations were made on general
inflorescence and anthesis, pollination mechanisms pollen release, seed
production, and seed shattering as well as overall seasonal growth
patterns.
Due to this season’s unusually early flowering (early April),
general observations were made on inflorescence, anthesis, and pollen
release patterns.
The mechanism of pollination was observed by noting the
specific pollinator the Gulf Coast Lupine attracts. Studies have observed
that most lupines producing blue, white, and yellow flowers are selffertilizers, although some crossing within (although not between) species
may occur (Mckee, 1946 and Ritchey, 1947). It has also been reported that
despite the fact that some plant species considered to be self- fertilizing,
seed setting is improved by insect visitation (Julen and Akerberg, 1948).
Seeds were collected, by means of a cheesecloth encasement
around 10 percent of the observed lupines (Figure 3), and counted to
quantify seed production Seed viability was identified according to physical
characteristics of the seed. The approximate dates of seed shattering and
the mechanism of seed dispersal were also noted. During each critical
phase photographs were taken for documentation. In addition to
phenological observations, all significant disturbances affecting the study
sites were noted.
140
120
Mean number of viable seeds produced
The Gulf Coast Lupine (Lupinus westianous) (Figure 1) is
one of Florida’s rare and endangered native plant species (Beckner,
1982). Initially listed in April 1987, only 15 populations have been
identified, each consisting of fewer than 1000 plants (Center for
Plant Conservation, 2006). This lupine is found in beach dune, scrub
habitats and disturbed areas (FWS, 2006). Some principal causes of
decline include destruction of natural habitat due to commercial,
residential and recreational development, lack of disturbance, and
low levels of genetic diversity within the Gulf Coast Lupine (Center
for Plant Conservation, 2006). This plant historically grew in scrub
gaps created by disturbances such as fire, until lack of disturbances
resulted in gap closure and excessive shading, thus decreasing
populations of this species (Center for Plant Conservation, 2006).
Because of the Gulf Coast Lupine’s affinity for disturbance, it is
often found during the preliminary stage of post-fire plant
succession (USDA Forest Service, 2006). In hurricane country, with
high humidity, moisture and human interference, fire is a naturally
rare occurrence in Gulf Coast Lupine habitats. Hurricanes and
tropical storms, however, are a constant threat during the summer
months, providing an alternative source of disturbance for Gulf
Coast Lupine establishment.
Walton County, Florida is home to several known and
protected populations of Gulf Coast Lupine, within Deer Lake State
Park and Topsail Hill Preserve State Park, where this study was
conducted (Figure 2). Due to its rarity, it is important to identify the
optimal conditions for plant growth and reproduction, as well as the
species’ phenology.
Phenology, the seasonal cycles of life, such as
germination or reproduction, reveal a specific set of traits crucial to
reproductive success (Rathcke and Lacey, 1985). Through
phenological studies, annual cycles of the plant are further
understood by examining responses to seasonal changes, flower
emergence, blooming patterns, fruit growth, and the dropping of
leaves. Understanding of flowering phenology, seed production and
species interactions are crucial to plant survival. Although recovery
plans are the ultimate stage of action, phenology provides the
foundation of designing strategies for specific species recovery
(Boersma et al., 2001). Through this knowledge, endangered species
are given the chance to survive and flourish.
KEY RESULTS
100
medium-large
30%
small-medium
70%
Figure 4. Observed size distribution of Lupinus
westianous within Deer Lake State Park, FL.
CONCLUSION
80
Due to observations of mean population
primary growth, viable seed production, size
distribution, and current disturbance patterns, the
study hypothesis has been supported; Topsail Hill
State Preserve produced more successful Gulf Coast
Lupine populations.
60
40
20
0
Topsail Hill
Deer Lake
Population Locations
Figure 6. Mean viable seed production within two
endangered Lupinus westianous populations in
Santa Rosa Beach FL.
REFERENCES
1.6
Anonymous. Centerforplnatconservation.org. Taken from web March 2006. Lupinus westianus var.
aridorum.
http://www.centerforplantconservation.org//ASP/CPC_ViewProfile.asp?CPCNum=2693.
small-medium,
37%
medium-large,
63%
Figure 1. Gulf Coast Lupine in vegetative growth state; April 2006.
Figure 5. Observed size distribution of
Lupinuswestianous
within Topsail Hill State Preserve, FL.
STUDY OBJECTIVES
Mean primary growth (cm./month)
1.4
1.2
Anonymous. 2006. U.S. Department of Agriculture Forest Service. Taken from web March 2006.
Fire Effects. http://www.fs.fed.us/database/feis/plants/forb/lupcau/fire_effects.html.
1
0.8
Anonymous. 2006. U. S. Fish and Wildlife Service 1. Taken from web March 2006. General
Statistics of Endangered Species.
http://ecos.fws.gov/tess_public/TessStatReport.
0.6
Beckner, J. 1982. Lupinus aridorum a new species from Central Florida. Phytologia. 50, 3: 209-211.
0.4
Boersma, D., Clark, A., Fagan, W., Hoekstra, J., and P. Kareiva. 2001. How Good Are Endangered
Species Recovery Plans? BioScience. 51, 8: 643-649.
Mckee, R. 1948. The Legumes of Many Uses. U.S. Department Agriculture Yearbook. 701-726.
0.2
Julen, G. and E.Akerberg. 1948. Insects and Seed Setting in Agricultural Plants. Abstract in Herbage
Abs. 18, 4: 899.
0
Topsail Hill
The objectives of this study are: 1) to observe the
phenological growth patterns of two Florida populations of
Lupinus westianous; and 2) to determine if flowering and seed
production differs between the two populations.
Deer Lake
Population Location
Figure 2. Map of coastal areas within Walton County, Florida. Study areas,
Deer Lake State Park (east H.W. 30-A) and Topsail Hill State Preserve
(west H.W. 30-A) are located approximately 17 miles of each other
(Miralda, 2006).
It has been hypothesized that areas of higher
disturbance will yield more flowering and higher seed production
than areas of low disturbance (Center for Plant Conservation,
2006). Because Gulf Coast Lupine relies heavily on disturbance, it
is expected that populations within Topsail Hill Preserve State Park
will have higher flowering and seed production due to relatively
recent disturbance by Hurricane Ivan and because few areas
within the park are inaccessible to visitors, thus increasing the
potential for disturbance.
Rathcke, B., and E. Lacey. 1985. Phenological Patterns of Terrestrial Plants. Annual Review of
Ecology and Systematics. 16: 179-214.
Figure 7. Mean primary growth observed in two endangered
Lupinus westianous populations in Santa Rosa Beach FL.
ACKNOWLEDGMENTS
I’d like to extend a special thank you to Dr. Julie Korb for her
support and help in conducting this study, and to the staff at Topsail Hill State
Preserve, Deer Lake State Park, and the Florida Department of Environmental
Protection Division of Recreation and Parks for their time, knowledge, and
encouragement.
Table 1. Phenological observations for study populations of Gulf Coast lupine within Topsail Hill State Preserve and Deer Lake State Park.
Sun Exposure
Surrounding Water Source
Inflorescence
Pollinators
Anthesis
Seed Shatter
Flower Color
Flower Size
Growth Pattern
Topsail Hill
direct, shade
Morris Lake (fresh)
late April
self, bees
early May
June
purple
small
sporadic
Deer Lake
direct
Gulf of Mexico (salt)
late April
self, rodent
early May
June
blue purple
medium
bunched
Additionally, I would like to thank Morgan Dezendorf-my eyes and
ears of the course.